This invention relates to a process of forming oxide films on a semi-conductor substrate and, more particularly, to a low temperature LPCVD process.
Production of semiconductor devices often requires the deposition of thin dielectric films on wafers. One technique that has been used to deposit thin films on semi-conductor substrates is low-pressure chemical vapor deposition (LPCVD). It is desirable to have low temperature processes in semiconductor manufacturing to meet the thermal budget requirements of the devices.
Previously, the conventional source materials for LPCVD oxide films have been SiH4, Si2H6 and TEOS (tetra ethyl ortho silicate). More recently, it has been demonstrated that using BTBAS (bis-tertiary-butyl-amino silane) as a source material provides a lower temperature LPCVD process for silicon nitride deposition with improved particulate performance and usable film uniformity.
Despite the previous work on nitride with BTBAS source materials, it is not known whether a good quality doped oxide can be deposited using BTBAS as a source such that it can be applied to gap fill applications successfully or at sufficiently low temperature to be compatible with back end processing.
The present invention is directed to further improvements in semiconductor processing.
In accordance with one aspect of the invention, a method utilizes BTBAS to form doped oxide at relatively low reaction temperatures.
In accordance with another aspect of the invention, a method utilizes BTBAS in gap fill applications.
Broadly, in accordance with one aspect of the invention, there is disclosed the process of low pressure chemical vapor deposition (LPCVD) of doped oxide film on a substrate. The process includes the steps of providing a substrate in an LPCVD reactor and flowing BTBAS and oxygen into the LPCVD reactor to react on the substrate to deposit an oxide film on the substrate. A dopant precursor is flowed into the LPCVD reactor to dope the oxide film as it is deposited on the substrate.
Optionally, a wet or dry anneal using O2 or N2 in the range of 600C-750C after deposition can be done to densify the oxide (USG, PSG, BPSG, other doped oxides) or to reflow and densify the BPSG film for gap fill applications.
It is a feature of the invention that the substrate comprises a semiconductor wafer.
It is another feature of the invention that the temperature of the LPCVD reactor is in a range of 400 C to 650 C, and preferably is in a range of 420 C to 550 C, and more preferably is below 500 C.
It is another feature of the invention that the dopant precursor is selected from a group consisting of PH3, TEPO (triethylphosphate), TMPi (trimethylphosphite), B2H6, TEB (triethylborate) and TMB (trimethylborate).
There is disclosed in accordance with another aspect of the invention the process of LPCVD of doped oxide film on a substrate comprising the steps of providing a substrate in an LPCVD reactor and flowing BTBAS and oxygen into the LPCVD reactor to react on the substrate to deposit an oxide film on the substrate at a select reaction temperature. Dopant precursor(s) is/are flowed into the LPCVD reactor to dope the oxide film as it is deposited on the substrate.
There is disclosed in accordance with a further aspect of the invention the process of LPCVD of doped oxide film on a substrate comprising the steps of providing a substrate in an LPCVD reactor and flowing BTBAS and oxygen into the LPCVD reactor to react on the substrate to deposit an oxide film on the substrate at a select reaction rate. Phosphorous precursor is flowed into the LPCVD reactor to dope the oxide film as it is deposited on the substrate at a relatively low reaction temperature.
There is disclosed in accordance with yet another aspect of the invention the process of LPCVD of oxide film for gap fill, a semiconductor substrate defining plural gaps to be filled by the undoped oxide film. The process comprises the steps of providing the semiconductor substrate in an LPCVD reactor and flowing BTBAS and oxygen into the LPCVD reactor to react on the substrate to deposit a relatively conformal oxide film on the substrate.
Optionally, a wet or dry anneal using O2 or N2 in the range of 600C-750C after deposition can be done to densify the doped oxide (USG, PSG, BPSG, other oxides) or to reflow and densify the BPSG film for gap fill applications.
It is a feature of the invention that the temperature of the LPCVD reactor is in a range of 500 C to 650 C in the case of undoped BTBAS oxide deposition for gap fill applications.
It is another feature of the invention to flow a dopant precursor into the LPCVD reactor to dope the oxide film as it is deposited on the semiconductor substrate to produce a doped glass film. The doped glass film is selected from a group consisting of As, B, P, Ge and/or F doped glass films.
It is a feature of the invention that the temperature of the LPCVD reactor is in a range of 400C to 650C.
Further features and advantages of the invention will be readily apparent from the specification and from the drawings.